The Knicks probably still need a veteran backup center, a big banger to come off the bench to help Joakim Noah and Spanish rookie Willy Hernangomez.

But 7-footer Marshall Plumlee, fresh off his senior season at Duke, will give it his best shot to be part of that mix — and at least will give Noah and Hernangomez a physical battle in October.

Plumlee, who was on the Knicks summer league team in Orlando, told The Post he has been invited to Knicks training camp. Thursday, Plumlee signed a partially guaranteed three-year deal — the first year is fully guaranteed at the league minimum of $565,000 and the final two years are non-guaranteed, according to an NBA source. By extending a three-year offer, the Knicks are forced to dip into their eroding cap space for the money, but ensure his salary won’t skyrocket if he has success. On the flip side, Plumlee is the lone undrafted player to get a full guarantee off summer league.

His two brothers, Miles and Mason, are in the NBA, drafted as first-round picks. Marshall is taking a different route. He was not drafted last month and already has a career lined up after basketball. He joined the Army Reserve two years ago in a ceremony on the Duke campus. When he hangs up his basketball sneakers, he’s going straight to the Army.

In four summer league games, Plumlee struggled adjusting to the nuances of the triangle offense, but is clearly a talkative, physical presence on defense. Knicks coach Jeff Hornacek likes his centers to be chatty on the court, directing traffic. Plumlee averaged 6.0 points and 4.8 rebounds in 21 minutes per game in Orlando.

Plumlee, who turns 24 next week, feels he has the edge on his brothers in the grit department, both of whom also played at Duke.

Mason and Miles Plumlee play against each other in 2015.Anthony J. Causi

“I don’t mind getting my hands dirty more than they do and getting my nose in there and getting physical,’’ Plumlee said. “I feel the Knicks have given me a look for a certain reason. I need to be comfortable in my role to bring energy and physicality inside. That’s something I’m comfortable bringing to the table. If I keep working at it, I can help the Knicks in some way.’’

Miles, now with Milwaukee, recently finished his fourth season. Mason, drafted by the Nets, finished his third season with Portland.

“In certain ways I look up to them both,’’ Plumlee said. “We’re all our own unique player, but nobody’s run a more similar race than my brothers. I’ve watched how they transitioned from college to the NBA. When I’m hitting roadblocks and frustrations, I hit them up for advice. In terms of actual skill set, it’s a little different, but we all bring energy and athleticism.”

Marshall claims he has a better jumper than Miles and Mason, but that might be brotherly boasting. He didn’t display it in Orlando. If he does hit the mid-range jumper, he’ll have a genuine shot at making the club — even if the Knicks use his spot on the 15-man roster to have him play in Westchester.

“It’s definitely been a learning curve for me,’’ Plumlee said. “But it’s an exciting process. I feel I’m getting better at it each day. It’s different, being given new responsibilities I’m not used to having before. It’s an exciting transition.’’

If the Knicks hold training camp at West Point for a third straight year, Plumlee will feel right at home. He could not specify his current Reserve assignment because it is classified, nor would he reveal what the Army has in store for a 7-footer in the future.

“Everyone tried to make it one or another — that he’s giving up basketball for the Army,’’ Plumlee said. “You can do both. That’s what I’m doing. After my basketball career, I have an exciting career waiting for me in the Army.”

After a jittery start in which he combined to shoot 4-of-18 in the first two summer league games, undrafted Wichita State guard Ron Baker came on strong. In his fourth game Wednesday, Baker collected 22 points, nine rebounds, five assists and five steals while making four 3-pointers. He’s a favorite of Hornacek’s and already has been invited to training camp. He likely will get a small guarantee. With Langston Galloway gone, Baker’s chances of making the squad improved dramatically.